On Wed, Jul 22, 2020 at 05:22:31PM +0100, Marc Zyngier wrote:
> So far, vcpu_has_ptrauth() is implemented in terms of system_supports_*_auth()
> calls, which are declared "inline". In some specific conditions (clang
> and SCS), the "inline" very much turns into an "out of line", which
> leads to a fireworks when this predicate is evaluated on a non-VHE
> system (right at the beginning of __hyp_handle_ptrauth).
>
> Instead, make sure vcpu_has_ptrauth gets expanded inline by directly
> using the cpus_have_final_cap() helpers, which are __always_inline,
> generate much better code, and are the only thing that make sense when
> running at EL2 on a nVHE system.
>
> Fixes: 29eb5a3c57f7 ("KVM: arm64: Handle PtrAuth traps early")
> Reported-by: Nathan Chancellor <natechancellor@xxxxxxxxx>
> Reported-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
> Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
Thank you for the quick fix! I have booted a mainline kernel with this
patch with Shadow Call Stack enabled and verified that using KVM no
longer causes a panic.
Reviewed-by: Nathan Chancellor <natechancellor@xxxxxxxxx>
Tested-by: Nathan Chancellor <natechancellor@xxxxxxxxx>
For the future, is there an easy way to tell which type of system I am
using (nVHE or VHE)? I am new to the arm64 KVM world but it is something
that I am going to continue to test with various clang technologies now
that I have actual hardware capable of it that can run a mainline
kernel.
Cheers,
Nathan
> ---
> arch/arm64/include/asm/kvm_host.h | 11 ++++++++---
> 1 file changed, 8 insertions(+), 3 deletions(-)
>
> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> index 147064314abf..a8278f6873e6 100644
> --- a/arch/arm64/include/asm/kvm_host.h
> +++ b/arch/arm64/include/asm/kvm_host.h
> @@ -391,9 +391,14 @@ struct kvm_vcpu_arch {
> #define vcpu_has_sve(vcpu) (system_supports_sve() && \
> ((vcpu)->arch.flags & KVM_ARM64_GUEST_HAS_SVE))
>
> -#define vcpu_has_ptrauth(vcpu) ((system_supports_address_auth() || \
> - system_supports_generic_auth()) && \
> - ((vcpu)->arch.flags & KVM_ARM64_GUEST_HAS_PTRAUTH))
> +#ifdef CONFIG_ARM64_PTR_AUTH
> +#define vcpu_has_ptrauth(vcpu) \
> + ((cpus_have_final_cap(ARM64_HAS_ADDRESS_AUTH) || \
> + cpus_have_final_cap(ARM64_HAS_GENERIC_AUTH)) && \
> + (vcpu)->arch.flags & KVM_ARM64_GUEST_HAS_PTRAUTH)
> +#else
> +#define vcpu_has_ptrauth(vcpu) false
> +#endif
>
> #define vcpu_gp_regs(v) (&(v)->arch.ctxt.gp_regs)
>
> --
> 2.28.0.rc0.142.g3c755180ce-goog
>
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